BMC Public Health
BioMed Central
Open Access
Research article
Prevalence of cardiovascular risk factors and the metabolic syndrome in middle-aged men and women in Gothenburg, Sweden Lennart Welin*1,2, Annika Adlerberth2, Kenneth Caidahl2,4, Henry Eriksson2, Per-Olof Hansson2, Saga Johansson3, Annika Rosengren2, Kurt Svärdsudd5, Catharina Welin2,6 and Lars Wilhelmsen2 Address: 1Department of Medicine, Lidköping Hospital, Lidköping, Sweden, 2Cardiovascular Institute, Sahlgrenska Academy, University of Gothenburg, Sweden, 3AstraZeneca, Mölndal, Sweden, 4Karolinska Institute, Stockholm, Sweden, 5Department of Public Health and Caring Sciences, Uppsala University, Sweden and 6Institute of Health and Care Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden Email: Lennart Welin* -
[email protected]; Annika Adlerberth -
[email protected]; Kenneth Caidahl -
[email protected]; Henry Eriksson -
[email protected]; Per-Olof Hansson -
[email protected]; Saga Johansson -
[email protected]; Annika Rosengren -
[email protected]; Kurt Svärdsudd -
[email protected]; Catharina Welin -
[email protected]; Lars Wilhelmsen -
[email protected] * Corresponding author
Published: 8 December 2008 BMC Public Health 2008, 8:403
doi:10.1186/1471-2458-8-403
Received: 1 April 2008 Accepted: 8 December 2008
This article is available from: http://www.biomedcentral.com/1471-2458/8/403 © 2008 Welin et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract Background: Random samples of 50-year-old men living in Gothenburg have been examined every 10th year since 1963 with a focus on cardiovascular risk factors. The aims of the study were to acquire up-to-date information about risk factors in the fifth cohort of 50-year-old men and women, to re-examine those who were 50 years of age in 1993, and to analyse the prevalence of the metabolic syndrome (MetSyn) using different definitions. Methods: A random sample of men and women born in 1953 were examined in 2003–2004 for cardiovascular risk factors. Men born in 1943 and that participated in the examination in 1993 were also invited. Descriptive statistics were calculated. Results: The participation rate among men and women born in 1953 was 60 and 67% respectively. Among men born in 1943, the participation rate was 87%. The prevalence of obesity was from 15 to 17% (body mass index, BMI ≥ 30) in the three samples. The prevalence of known diabetes was 4% among the 50-year-old men and 6% among the 60-year-old men, and 2% among the women. Increased fasting plasma glucose varied substantially from 4 to 33% depending on cut-off level and gender. Mean cholesterol was 5.4 to 5.5 mmol/l. Smoking was more common among women aged 50 (26%) than among men aged 50 (22%) and 60 years (15%). The prevalence of the MetSyn varied with the definition used: from 10 to 15.8% among the women, from 16.1 to 26% among 50-yearold men, and from 19.9 to 35% among the 60-year-old men. Only 5% of the men and women had no risk factors. Conclusion: This study provides up-to-date information about the prevalence of cardiovascular risk factors and the MetSyn in middle-aged Swedish men and women. Different definitions of the MetSyn create confusion regarding which definition to use.
Page 1 of 9 (page number not for citation purposes)
BMC Public Health 2008, 8:403
Background Since the landmark Framingham Heart study in 1948 [1], there have been several hundred prospective cohort studies on cardiovascular disease and associated risk factors. In Gothenburg the first cohort of 50-year-old men (the Study of Men Born in 1913) was examined in 1963 [2]. Younger cohorts of 50-year-old men (i.e. men born in 1923, 1933, and 1943) have later been examined every 10th year [3-5]. The present study adds new data by including the 5th cohort of 50-year-old men (men born in 1953). We have also examined 50-year-old women (born in 1953) in addition to a follow-up examination of the 4th cohort of 50-year-old men (born in 1943), now aged 60 years. With an increasing prevalence of excess body weight and obesity in the population, the metabolic syndrome (MetSyn) has attracted considerable attention during the past decade as an important risk factor in cardiovascular disease. There are at least five definitions of Metsyn [6], which create considerable confusion regarding which definition to use. Furthermore, with so many definitions, it is difficult to obtain consistent research results. The aim of the present study was twofold: (1) to acquire current information about risk factors in cardiovascular disease in a middle-aged Swedish population and (2) to analyse the prevalence of the MetSyn using three popular definitions.
Methods Participants The study population consists of three cohorts: one third of all men (n = 993) and women (n = 994) born in 1953 and living in Gothenburg in 2003 were randomly sampled from the population register and invited to the examination. Gothenburg, which is a maritime and industrial city on the West coast of Sweden, is the second largest city in Sweden with approximately 450,000 inhabitants. The third cohort, men born in 1943, was a random sample in 1993 and now consists of all persons who were examined in 1993 (n = 798, 55% of those invited), except for those individuals that had died (n = 34) or moved abroad (n = 15). This leaves 749 men, now aged 60 years that were invited to participate in the present study. Based on those individuals examined, the participation rate was 60% (595 of 993) among men born in 1953, 67% (667 of 994) among women born in 1953 and 87% (655 of 749) among men born in 1943. Examination procedures The examinations took place between August 2003 and December 2004. All participants were mailed a question-
http://www.biomedcentral.com/1471-2458/8/403
naire on smoking habits and physical activity during leisure time. Each item was rated on a scale from 1 to 4, where 1 = no physical activity, 2 = moderate activity (e.g. walking, riding a bicycle and light gardening) for a minimum of 4 hours per week, 3 = regular, strenuous activity for a minimum of 3 hours per week and 4 = athletic training (competitive sports regularly). Regular smoking was defined as smoking at least one cigarette per day. Exsmokers were defined as having quit smoking at least one month before they mailed the questionnaire. A snuff taker (snuffer) is a person who uses snuff (wet tobacco) daily. The participants also answered questions about chest pain, psychological stress, family history of cardiovascular disease and cancer (parents and siblings), previous and current medical history and ongoing medication. Psychological stress was rated on a six-point scale with 0 = no stress, (1–3 = various grades of intermediate stress), 4 = continuous stress during the past year and 5 = continuous stress during the past 5 years. Diabetes was defined as having a physician's diagnosis of diabetes. Hypertension was defined as a physician's diagnosis and/or systolic blood pressure ≥ 140 and/or diastolic blood pressure (phase 5) ≥ 90 (physician measurement) and/or treatment for hypertension. Individuals who returned the questionnaire were invited to the examination, which was performed in the morning after an overnight fast. One reminder was sent out to the participants who did not return the first questionnaire but after that no further action was taken. The results are based solely on those persons that were examined. The study was done in the morning. The participants were asked to fast overnight. A question relating to when they had last eaten revealed that close to 90% had complied with the request to fast. A study nurse measured height (cm) and weight (kg) with indoor clothing and without shoes. Waist circumference was measured at the level of the umbilicus (cm) and hip circumference at the level of the anterior iliac crest (cm) with the participant standing and breathing normally. After five minutes of rest, blood pressure was measured automatically in the right arm in the seated position with the OMRON 711 monitor. A 12lead electrocardiogram was recorded with the participant relaxed and supine. Blood samples (fasting state) were taken for analysis of plasma glucose, serum total cholesterol, high-density lipoprotein (HDL) cholesterol and serum triglycerides (standard methods at the accredited university hospital laboratory in Gothenburg). During 2002, the analysis equipment at the laboratory was upgraded from Hitachi 917 Roche to Modular Roche, which resulted in an 11% increase of the mean HDL cholesterol levels [Flenner E, personal communication]. Lowdensity lipoprotein (LDL) cholesterol was calculated
Page 2 of 9 (page number not for citation purposes)
BMC Public Health 2008, 8:403
http://www.biomedcentral.com/1471-2458/8/403
using the Friedewald formula [7]. Blood samples were frozen (-70°C) until further analysis. After the first part of the study was completed, the participants were served a light breakfast. During breakfast, they completed another questionnaire on social and psychosocial factors, social network [8], education, working times, various complaints, sleeping habits and self-ratings on a seven-point scale regarding their health, economy, family situation, memory, energy, sleep, ability to handle stress, and simultaneous capacity [9]. A physician administered a structured interview after breakfast. The same physician also checked the questionnaires. The physician measured blood pressure using exactly the same method as in 1963 [2], i.e. with a mercury sphygmomanometer (cuff size 12 × 23 cm) in the right arm after five minutes of rest with the participant in the seated position. If potential medical problems were identified, the participants were referred for further workup (severe hypertension, chest pain or other alarming symptoms). All participants received a letter with the results from the examination and, if needed, advice about lifestyle changes. The review board of the Ethics Committee at the University of Gothenburg approved the study. All participants signed a written informed consent form. Statistical methods The analyses were conducted using the SAS statistical software package [10]. Descriptive statistics were used. The prevalence of the MetSyn was calculated based on three definitions recently reported in the literature (Table 1).
Results Demographic data Demographic data are shown in Table 2. Higher education (university/college) was most common among the 50-year-old women. A higher proportion of the 50-yearolds (men and women) were born abroad (23%) as compared with the 60-year-old men (16%). Self-reported diseases and family history In one of the questionnaires the participants were asked about various common diseases (Table 2). Cardiovascular diseases and intervention procedures were more commonly reported by the 60-year-old men than by the 50year-old men and women. Between 36 and 38% of the participants reported a family history of myocardial infarction, 25–27% reported a family history of stroke, and 23–25% reported a family history of diabetes. Anthropometric measurements Details on anthropometric variables are given in Table 3. The prevalence of obesity (Body mass index [BMI] ≥ 30 kg/m2) was 15% among 50-year-old men and women and slightly higher (16.6%) among 60-year-old men. Using the WHO cut-off for waist/hip ratio (>0.85 for women, >0.90 for men, ref. 11), 38% of the women and 73% of the 50-year-old men and 79% of the 60-year-old men had abdominal obesity. Using the AHA criteria (Table 1, ref. 6, only waist circumference), 30% of the women and 22 and 30% respectively of the 50- and 60-year-old men had abdominal obesity. Using the International Diabetes Federation (IDF) criteria (Table 1, only waist circumference) the corresponding figures for women and men were 56% and 51–61% respectively.
Table 1: Three definitions of the metabolic syndrome.
NCEP 2001, ref 12 At least 3 of the following:
AHA 2005, ref 6 At least 3 of the following:
IDF 2005, ref 13 Waist circumference (Euripides) ≥ 94 cm (men), ≥ 80 cm (women) plus any 2 of the following:
1. Fasting P-glucose ≥ 6.1 mmol/l (≥ 110 mg/dl)
1. Fasting P-glucose ≥ 5.6 mmol/l (≥ 100 mg/dl) or drug treatment for elevated glucose.
1. Fasting p-glucose ≥ 5.6 mmol/l (≥ 100 mg/dl) or known type 2 diabetes
2. Blood pressure ≥ 130/≥ 85
2. Systolic BP ≥ 130 or diastolic BP ≥ 85 or treatment for hypertension
2. Systolic BP ≥ 130 and/or diastolic BP ≥ 85 or treatment for hypertension
3. Triglycerides ≥ 1.7 mmol/l (≥ 150 mg/dl)
3. Triglycerides ≥ 1.7 mmol/l (≥ 150 mg/dl) or drug treatment for elevated triglycerides
3. Triglycerides ≥ 1.7 mmol/l (≥ 150 mg/dl) or specific treatment
4. HDL-cholesterol
